Conventionally, this type of resolver includes a stator and a rotor, and outputs an output signal corresponding to a rotational angle of the rotor relative to the stator by making use of a phenomenon that mutual inductance between the stator and the rotor changes corresponding to the rotational position of the rotor relative to the stator.
FIG. 24 is a view for explaining a conventional resolver. FIG. 24(a) is a view showing the structure of the conventional resolver, and FIG. 24(b) is a view for explaining the winding structure of each slot of the conventional resolver.
The conventional resolver 10 is, as shown in FIG. 24(a), a variable-reluctance resolver which includes a stator 11 in which excitation winding 14 of one phase and detection windings of two phases (SIN detection winding 16 and COS detection winding 17 (not shown in FIG. 24(a))) are wound around salient-pole portions 13, and a rotor 15 which is arranged rotatably relative to the stator 11. The rotor 15 is an eccentric rotor which is formed of only an iron core and has no winding, and gap permeance between the rotor 15 and the stator 11 changes in a sinusoidal manner with respect to a rotational angle θ. Therefore, according to the conventional resolver 10, as shown in FIG. 24(b), it is possible to detect the rotational angle with high accuracy by measuring the above-mentioned gap permeance.
Further, in the conventional resolver 10, detection windings of two phases (SIN detection winding 16 and COS detection winding 17 are wound around in respective slots 12 at one slot pitch (a state where the winding is continuously inserted into each slot without slot leap) (not shown in FIG. 24(a)). Also as shown in FIG. 24(b), the detection windings are wound such that the distribution of a voltage induced in each detection winding becomes the sinusoidal distribution (the distribution of number of turns (quantity) of each winding also becoming the sinusoidal distribution).
Due to such a constitution, the conventional resolver 10 can reduce high frequency components ranging from lower-order frequency components to higher-order frequency components contained in an output voltage thus enhancing the detection accuracy of a rotational angle.
However, the conventional resolver 10 has the structure shown in FIG. 24(a) and hence, it is difficult to wind the excitation windings and the detection windings around the salient poles so that the structure of an automatic winding machine becomes complicated, for example. In view of such circumstances, for example, patent document 1 and patent document 2 disclose an angle detection system which can form salient poles and a rotor using a metal sheet or the like while providing excitation winding and detection winding to a bobbin arranged on a stator side or printing excitation winding and detection winding to a multi-layered printed circuit board on a stator side.